On our Greyhawk we have to flip the screen to depress the check valve to get it to flow at all. If yours is flowing in but slowly that might not be the issue, but I thought I'd mention it - in case your check valve is the culprit too.
I'm with pconroy, check valve is not getting pushed off it's seat.
__________________
2015 Jayco Precept 35UN
Towing JEEP TJ with Roadmaster plates and bar w/Blue Ox Patriot brake
OR
an Aluma low bed trailer with HD Road King and/or Polaris RZR onboard
Was told to try flipping the screen around and I'm assuming what that did was press against the check valve, because now it's filling rapidly! Thank you everyone!